Trimmer mechanism for grinding machines



Nov. 10, 1942. 5. ca. BRADY TRIMMER MECHANISM FOR GRINDING MACHINESFiled March 5, 1941 5 Sheets-Sheet l v INVENTOR SAMUEL G-BRADY BY; 2' 5Z A TTORNE YS Nov. 10, 1942. s. a. BRADY TRIMMER MECHANISM FOR GRINDINGMACHINES Filed larch 3, 1941 3 Sheets-Sheet 2 INVENTOR SQMUEL G. BRADYMW $424M ATTORNEYS Nov. 10, 1942. s. G. BRADY 2,301,610

TRIMMER mncmmxsm FOR GRINDING MACHINES Filed March 3, 1941 5Sheets-Sheet 5 INVENTOR I SAMUEL G. BRADY BMW/WW A TTORNE YS PatentedNov. 10, 1942 UNITED STATE-S'PATENT OFFICE TRIMMER MECHANISM FORGRINDING MACHINES Samuel G. Brady, Detroit, Mich., assignor to The GearGrinding Machine Company, Hamtramck, Mich., a corporation of MichiganApplication March 3, 1941, Serial No. 381,584

4 Claims.

The invention relates to trimmer mechanisms for formed grinder wheelsand has more particular reference to a construction adapted to trimtangent curves.

In the trimming of formed grinder wheels for use in the grinding ofgears, splines, etc., the opposite sides of the wheel are fashioned byseparate diamond trimming points. It is also usual to trim theperipheral edge of the wheel by another trimming point, but the severalcurves formed by these points are separate from each other. With certainclasses of work it is desirable to trim contours having tangent curves,but difficulty is experienced in adjusting the trimmers to produce thisresult. Thus, if there is a slight misalignment of the adjacent curves,this will create a groove or ridge in the work being ground, which ishighly objectionable.

It is one of the objects of the instant invention to obtain aconstruction of trimming mechanism capable of trimming difficult curveswhich are exactly tangent to each other,

It is a further object to trim such curves by a single trimming point.

Still further, it is an object to associate this single trimming pointwith other trimmers for producing further tangent or substantiallytangent curves in the trimmed contour.

With these objects in view, the invention consists in the constructionas hereinafter set forth. In the drawings:

Fig, 1 is a side elevation of my improved trim mechanism, partly shownin central longitudinal section;

Fig. 2 is a plan view, some are in section;

Fig. 3 is an end elevation;

Fig. 4 is a diagram indicating the different centers of movement for thesingle trimming point and their relation to each other and to thecontour to be trimmed; and

Fig. 5 is a cross section on line While my improved trimmer is varioususes, I

tangent portions of which 5-5 of Fig. 1.

shall specifically describe an ar rangement for trimming grinder wheelsused in grinding splines.

As shown in Fig. 4, A is a portion of a shaft or other member providedwith a series of splines B in indexed relation to each other and wi hintermediate grooves C. The strength of such a structure fortransmitting torque stresses is greatly augmented if the splines areformed with curved fillets at the roots thereof. Also, the fillets ofadjacent splines should be tangent to the surface forming the bottom ofthe groove between applicable to.

. a member pivctally secured adjacent splines, as well as being tangentto the side faces of the splines. To accomplish this result, I havedevised a mechanism in which a single trimming point is alternatelymovable about a plurality of different centers and is locked frommovement about one center during its movement about another center. Thisin sures the exact tangency of the curves concentric with theirrespective centers.

More in detail, D is the base for my improved trimming mechanism whichis mounted upon the work carriage E of a grinding machine and is securedthereto by suitable means such as a depending flange D at one side ofthe carriage, the hook D for engaging a groove in the carriage, and anut D engaging a threaded shank of said hook to clamp the same. The baseD is further secured to the carriage by clamping bolts D The base D hasan upwardly extending portion D on which is mounted a verticallyextending member F. To the front face of the member F is pivctallysecured a member G to swing in a vertical transverse plane. The pivotalconnection is preferably formed by a pivot pin F extending through alongitudinal bore in the member F and having a tapered forward endportion F for engaging a correspondingly tapered bushing member G in themember G. This insures the holding of the member G in a fixed planewhile permitting its pivotal movement in said plane. The member G isfurther provided with a rearwardly extending lug G This lug is arrangedbetween adjustable stop members F and F preferably screws, engagingupwardly extending lugs F and F on opposite sides of the member F. Thearrangement is such that by adjusting the screws F F the amount ofmovement permitted to the lug G and consequently the amount of angularmovement of the member G on the pivot F may be limited.

H is a member vertically adjustably secured to the front face of themember G, which latter is provided with a grooved guideway G engaging aspline H on the members H. H are clamping bolts for securing the memberH in different positions of adjustment, which bolts engage laterallyprojecting ears H and pass through vertical slots G in cars G on themember G. I is to the front face of the member H by means of the pivotpin I having the tapering rear portion I which engages ccrrespondingtapering bushing H in the member H. The member H is also provided withan annular groove H which surrounds and is diamond trimming point J ismovable about the 7 axis of the pivot pin I to describe an arc of aradius equal to the distance between said point and said axis. Also, byswinging the members I and 111 about the axis of the pivot F, thediamond point will describe an arc of a radius equal to the distancebetween the same and said axis. It

will also be understood that as the diamond point J is located betweenthe axes of the pivot pins I and F, the arcs traced by movement abouttheir respective axes will be of reverse curvature, but tangent to eachother. However, it is necessary that movement around one axis must beprevented during movement about the other axis, as otherwise anirregular curve would be traced which would be non-concentric witheither axis.

For performing the specific trimming operation of a grinder wheel forgrinding a spline shaft as illustrated in Fig. a, movement of thetrimming point about the axis of the pin I is used for trimming the rootfillet grinding portion of the grinder wheel. n the other hand, movementof the diamond point about the axis of the pin F is used for grindingthe portion of the grinder wheel which forms the bottom of the groove C.The length of the arc concentric with the axis F is limited by the stopsF and F and it is also necessary to limit the length of the arcconcentric to the axis I so that the curve will be tangent to theportions of the grinder wheel which grind the side faces of the splines.These side faces are trimmed by separate diamond point trimmers, but assuch trimming mechanism is similar to that which has heretofore beenused for the same purpose, it is not necessary to describe the same inthe instant application. However, as above stated, it is essential thatthe length of the arc described about the axis I should be limited.

Also, it is necessary to provide locking means for holding the member Iagainst pivotal movement while the trimmer point is describing the areabout the axis F. As illustrated, the looking means for the member Icomprises a locking bolt or pin K which is arranged in a longitudinalbore centrally within the member J. The rear end of the pin K has acylindrical portion K of smaller diameter, terminating in a taperingportion K The portion K engages a correspondingly shaped bushing K inthe member H. This bushing is so located that when engaged by the pin K,the diamond point will be in a plane that is common to both axes I andF. In other words, the diamond is located at the point of tangency ofthe two curves, respectively, described about the axes I and F. The pinK in its unlocked position is also utilized. for limiting the arcuatemovement of the member I about the axis of the pin I. In this itcooperates with a pair of adjustable stops L and L, preferably formed byscrews engaging threaded apertures in the member H and extending intothe annular groove H to be substantially tangent thereto. Thus, when themember I is turned about the pivot I in either direction from its lockedposition, the portion K of the pin K will contact with one or the otherof the stops L and L, which will prevent further rotation. The belt orpin K may be operated by a lever M which is fulcrumed at M on the memberI and extends inward through a recess therein intersecting with the borewhich holds the bolt. The inner end of the lever M has a pin portion Mextending into a recess in the bolt with sufficient clearance to permita relative angular movement of the lever. A spring K normally urges thebolt toward its locking position, and the lever M retracts the boltagainst the tension of this spring. i

The grinder wheel to be trimmed is indicated in dotted lines at N (Figs.1 and 4) and is mounted on a suitable support (not shown). To facilitatesetting of the trimming mechanism, the member F is laterally adjustablysecured to the portion D of the member D by clamping bolts 0. Thesebolts pass through slotted bearings in the base of the member F, and aspline O on this base engaging a transverse groove in the portion Dprevents movement in any other direction. Screws 0 engaging ears 0projecting upwardly from opposite sides of the portion D and bearingagainst the base portion of the member F form a means for adjusting thesame. For adjusting the member G about the pivot F, I have provided ascrew P engaging a threaded bearing in an upwardly projecting ear P onthe member, F. The inner end of this screw has a loose swivel engagementWith a pin P rotatively engaging a recess in the lug G extendingoutwardly therefrom. The opposite end of the screw P is provided with acrank handle P and by turning this crank handle, the member G may bemoved in either direction until arrested by the stops F and F OperationIn setting the trimming device for trimming a grinder wheel, the shank Jof the diamond point trimmer J is adjusted in the member J so as tolocate this point a predetermined distance from the axis of the pin I.This will determine the radius of the curve for. forming the root filletB of the spline B. The member H is then adjusted on the member G, so asto space the axes of the pins I and F a predetermined distance from eachother. This may be accomplished by loosening the bolts H sliding thespline H in the groove G and then again tightening the bolts. Thespacing between these axes should be equal to the length of radius forthe curve B plus the desired length of radius for forming the curve ofthe bottom B of the recess C. After such adjustment, the table E ismoved to bring the diamond point into the vertical axial plane of thegrinder wheel N, the member I being in its locked position. The grinderwheel is then adjusted downward into engagement with the trimming point,after which the crank handle I is turned to swing the members G, H, Iand J about the axis of the pin F. This will trim the periphery of thegrinder wheel to a concave contour, corresponding to the bottom B of thespace between splines. When the trimmer point has completed itsoperation and is at one end of its movement, as for instance limited bythe stop F the leverN is actuated to withdraw the locking bolt K, andthis same lever is then used to swing the members I and J about the axisof the pin I. The starting point of this movement is the end of the arcB so that the curve B will be tangent thereto. The limit of swingingmovement about the pin I is determined by the adjustment of the stop L,and this is so set that the curve will be substantially tangent to theside B of the spline B, which is above the root fillet B. The sameoperation is performed when the trimmer point is at the opposite end ofits movement about the axis of the pivot F so as to trim the grinderwheel for forming the root fillet of an adjacent spline.

It will be understood that the portions of th grinder wheel which grindthe sides B of the splines B are trimmed by independent trimmers.Therefore, the original setting of the stops F F and L, L is such as tobring the arcs B substantially tangent to these sides. Exact tangency isnot essential "as long as the arcs B do not undercut the grinder wheelat their point of juncture with the sides B It is therefore preferableto adjust the stops W, F so as to permit a slight over movement aroundthe axis of the pin F which will space the centers of the two fillets Bslightly farther apart. This will avoid the formation of any undercut inthe grinder wheel between the portions trimmed by the diiTerenttrimmers.

What I claim as my invention is:

1. In a trimming mechanism, the combination with a trimmer point, of anarm carrying said point angularly movably about a pivot on one sidethereof, a second arm to which said first arm is pivoted angularlymovable about a pivot on the opposite side of said point, releasablemeans for normally locking said arms to each other when relativelypositioned to hold said point in a plane common to both said pivotsduring the angular movement of the last mentioned arm about its pivot,an adjustable stop for limiting the movement of said last mentioned armwhile permitting said first mentioned arm when unlocked to moveangularly about its pivot, and an adjustable stop for limiting theangular movement of said first mentioned arm.

2. In a trimming mechanism, the combination with a trimmer point, of anarm carrying said point angularly movable about a pivot on one sidethereof, a second arm to which said first arm is pivoted angularlymovable about a pivot on the opposite side of said point, a bolt fornormally locking said arms to each other when relatively positioned tohold said point in a plane common to both said pivots during angularmovement of the last-mentioned arm about the last-mentioned pivot, anadjustable stop for limiting the movement of said last-mentioned arm, alever for releasing said bolt constituting a handle for moving saidfirst-mentioned arm angularly about said first-mentioned pivot, and anadjustable stop for limiting the angular movement of saidfirst-mentioned arm.

3. In a trimming mechanism, the combination with a trimmer point, of anarm carrying said point angularly movable about a pivot on one sidethereof, a second arm to which said first arm is pivoted angularlymovable about a pivot on the opposite side of said point, a bolt fornormally locking said arms to each other when relatively positioned tohold said point in a plane common to both of said pivots, a screw foractuating said last-mentioned arm about said last-mentioned pivot andfor holding the same in each position of adjustment, said screw beingprovided with a crank handle for rapid rotation of the same,

, spaced adjustable stops for limiting tht movement in oppositedirections of said last-mentioned arm, a lever for releasing said boltwhen said lastmentioned arm is in contact with one or the other of saidstops, said lever constituting a handle for rotating saidfirst-mentioned arm about said first-mentioned pivot, and spacedadjustable stops for limiting the angular movement of saidfirst-mentioned arm.

l. A trimming mechanism comprising a frame, a member pivotally supportedon said frame, a second member secured to said first member to beradially adjustable in relation to the pivot, a third member pivotallysecured to said second member, a trimmer point carried by said thirdmember and radially adjustable in relation to the second pivotalconnection, a locking belt for normally holding said third and secondmembers relativcly positioned to hold said trimmer point in a planecommon to both pivots, a screw for angularly adjusting said first memberon said frame and for holding the same in each position of adjustment,said screw being swiveled to said firstmentioned member and providedwith a crank handle for rapid rotation of the same, spaced screw stopsfor limiting the movement of said first member on said frame in oppositedirections, a lever for releasing said bolt when said first member is incontact with either one of said stops, said lever constituting a handlefor rotating said third member about its pivot, and spaced screw stopsfor limiting angular movement of said third member in oppositedirections.

SAMUEL G. BRADY.

